The instructions below are for moving GlassWire to another HD, but it's the same for backing up the database and moving it due to a reinstall of Windows. I hope this helps!
To move your database to another HD please create a "glasswire.conf" file in notepad with these two lines only (the lines in quotes):
This file should be copied to the c:\programdata\glasswire\service folder
The database path is set to D:\glasswire\ folder in the file sample, but you can change the path to something else.
You should restart the GlassWire service when the file is copied.